The present invention relates to measurement of a process variable in an industrial process. More specifically, the present invention relates to measurement of such a process variable using a primary element placed in the flow.
Industrial processes are used in the production of many types of process fluids. Examples include oil refineries, paper pulp manufacturing, chemical manufacturing, etc. In an industrial process, it is necessary to monitor operation of the process in order to accurately control the process. For example, “process variables” such as flow rate, temperature, pressure, level, etc. of the process can be monitored by process variable transmitters and used to provide the information to another location such as a central control room. In many instances, there are a number of different technologies or configurations of a process variable transmitter which can be used to measure a process variable. The particular technology and configuration can be selected based upon design constraints, desired accuracy, budgetary concerns, or other criteria.
Various technologies are known for measuring flow of a process fluid in an industrial process. Examples include differential pressure, magnetic, coriolis, vortex, and thermal mass based flow sensors. One general technology includes the use of a circuitry to measure a differential pressure and responsively estimate flow based upon the differential pressure. For example, a restriction can be placed in a pipe which carries a flow of process fluid. As the process fluid moves past the restriction, a differential pressure will be developed on either side of the restriction. This differential pressure can be measured and correlated with flow rate of the process fluid.
The particular installation of a flow measurement system typically requires a great deal of customization based upon the selected technology, the configuration of the process, the fluid being monitored, the diameter of the piping, the expected flow rates, as well other considerations. This customization is expensive and increases the amount of time required to install a process variable transmitter and ensure that it is providing accurate measurements. Further, the customization is often performed while the plant which implements the process is being constructed. For example, during manufacture of a plant, it may be known that a particular process variable measurement must be obtained at a particular location, however, it may not be readily apparent what technology should be used to obtain the process variable, or even if measurement of the process variable is necessary. This can introduce delays in the construction of a new facility as well as increase costs.